I was in a large construction project in Bellevue, WA the other day. 60 feet down and sump pumps running 24 hours a day to keep the ever-existant water table from flooding the concrete forms.

It made me pause. What keeps the water back once the building is completed. LOTS of sites, some not nearly so deep, need 24 hour a day sump pumps or the basements, tunnels, etc will fill with water.

Now, I would expect that all of these sites have back-up generators, but for how long? what if outages last days and fuel isn't available?

Lots of mechanical systems reside in basements of these buildings. Someone out there works in one, knows the back-up limitations, etc. I'd love to hear about them.

-- Randers (coyotecanyon@hotmail.com), December 12, 1999

Answers

Maybe someone from New Orleans can tell us about that cities water problems.

It is my understanding that New Orleans is mostly below the level of the Mississippi river, with the water being held back by levees that surround the city. These levees, however, suffer a high degree of seepage which results in millions of gallons of river water leaking through them each day.

In order to keep the city from becoming quickly submerged, huge pumps all over the perimeter of the city run 24 hrs a day, just to pump this water back into the river.

Perhaps someone from New Orleans can 1) verify this, and 2) guesstimate how long it would take the river to reclaim their city if the pumps suddenly decide to stop......

-- (cavscout@fix.net), December 12, 1999.

Think about water pipes freezing.

In northern climates, if the power is off, buildings freeze in a day or two. Most buildings have three systems: cold water, hot water, and sprinkler system. The sprinkler system has no shut off valve, no way to drain.

Once the power is on, the building will be flooded in the upper floors as well.

All this will end badly.

-- David Holladay (davidh@brailleplanet.org), December 12, 1999.

Hey,

You don't have to go that far to see flooding of basements.

I have 2 sump pump in my house and installed a batterie/solar (2400w) backup system.

-- Rickjohn (rickjohn1@yahoo.com), December 12, 1999.

Not all sprinkler systems are "wet" charged.

In a building I was in, oh, 12 years ago, the insurance company required the old sprinkler system to be replaced with a "dry" system.

In other words, the set of pipes was full of pressurized air (from the pressurized water behind it, pushing).

The purpose of this system was to prevent freeze/thaw cycles and burst pipes.

of course, this was zoned as an "uninhabited " building and basically used for warehousing, so the possibility of freezing temps was not too remote.

-- plonk! (realaddress@hotmail.com), December 12, 1999.

The industrial grade sprinkler systems that I am familiar with do indeed have shutdoff valves. You just won't find them out in the open next to the drinking fountain. They are frequently locked away in utility closets or found with the other guilding utilites. Any building that has a level below the water table would be in trouble with an extended outage. The flood level would equalize with the water table and stop there.

It would be like being in a sub when someone opened the screen door.

-- Squid (Itsdark@down.here), December 12, 1999.

Anyone remember the huge undergraound flood in Chicago in about 92? Basements of a bunch of buildings were flooded and brought down systems. I believe the board of trade closed for awhile, also.

Was that in any way the type of scenario mentioned above?

-- Duke 1983 (Duke1983@AOL.com), December 12, 1999.

Duke,

No..that was caused by workers sinking pilings through the bottom of the Chicago River into a underground tunnel system that was linked to a number of basements in the downtown area...What a mess that was!

-- TM (mercier7@pdnt.com), December 12, 1999.

Duke,
the above post refered to water that is always seeping into a building because it is lower than the water table. but its not seeping as fast as the incident you mention in Chicago.

The recent "Chicago Flood" was real fluke thing that happened because there just "happens" to be a system of underground small-scale railway tunnels that run throughout downtown Chicago.

These (now abandoned) tunnels were originally used to haul coal, mail and other deliveries to the large buildings without clogging up the streets (unlike NYC).

Most buildings had "sort of" sealed up, or caged off the old entrances to these abandoned tunnels (some of which ran beneath the Chicago River).

when a piling was driven into the bed of the Chicago River in the wrong place, it punched a hole in the ceiling of one of the tunnels. this allowed water to fill the tunnels at a tremendous rate, this had never happened before.

sub-basements and other below ground floor areas with old tunnel access were completely flooded within a day.

Initial FOF (which failed) included truckloads of mattresses from the Salvation Army dumped into the swirling, sucking whirlpool. I think they ended up waiting until everything filled up and the pressures equalized somewhat before they could plug up the hole.

Fascinating to watch though, bunch of guys in suits with hardhats on standing around on a bridge watching a huge disaster happening just below them and there's nothing they can do.

if you were on the bridge, you might be inclined to look at the whirlpool and say "that's cool" or "eh, no big deal" except of course, all the big buildings in the surrounding area were filling up with water to meet the level of the Chicago River. You couldn't tell this from the outside though.

-- plonk! (realaddress@hotmail.com), December 12, 1999.

sorry... "underground tunnel" is a bit redundant. The tunnels had been abandoned years earlier.

-- TM (mercier7@pdnt.com), December 12, 1999.

Just got back from some MORE last minute preps, and ?this?. You must be bored today Randers, try some serious prepping. It will help fill the voids. But in the interest of science.....

I've worked on boat houses on the Columbia River that were built with CONCRETE hulls/foundations. What do you suppose keeps them afloat (water out) Randers? Perhaps you should take a toy boat to your next bath, and perform that ancient, lost art form, called "think about it". Geez!

MHA, I'm sure looking forward to Jan 1!

Oh, by the way LOTS of sites don't need 24hr a day RUNNING sump pumps! GAG.

-- Michael (mikeymac@uswest.net), December 12, 1999.

-- no-one (noway@no.how), December 14, 1999.